Method and apparatus for filling containers



1960 c. vos'r 2,949,711

WTHOD AND APPARATUS FOR FILLING CONTAINERS Filed July 2, 1956 2 Sheets-Shut 1 INVENTOR CLARENCE W. 'VOGT (E Q Q m uu HIS ATTORNEYS Aug. 23, 1960 C. W. VOGT METHOD AND APPARATUS FOR FILLING CONTAINERS Filed July 2, 1956 2 Sheets-Sheet 2 CLARENCE W. VOGT BY .Mam F12 79m IS ATTORNEYS package.

ijnite States Patented Aug. 23, 1960 IVIETHOD AND APPARATUS FOR FILLING CONTAINERS Clarence W. Vogt, Weston, Conn. (Rte. 4, Westport, Conn.)

Filed July 2, 1956, Ser. No. 595,249

18 Claims. (Cl. 53-24) This invention relates to methods and apparatus for forming and filling packages with flour, pie-dough and cake mixes, granulated sugar and brown sugar, and other fluent and finely divided materials, and it relates more particularly to improvements in methods and apparatus of the type disclosed in my copending applications Serial No. 556,158, filed December 27, 1955, and Serial No. 585,775, filed May 18, 1956.

In the last-mentioned application, I have disclosed an apparatus by means of which a sheet of thermoplastic material can be deformed by vacuum or otherwise to form a plurality of pockets or receptacles therein which are received in a supporting mold. Finely divided or fluent materials are blown into the pockets to fill them and the pockets are then closed and sealed by applying a cover sheet over the open faces of the pockets and sealing or otherwise securing the cover sheet to the pocket-containing sheet. Apparatus of the kind described can be operated at extremely high speed with moderate air pressures for blowing or introducing the finely divided fluent materials into the pockets. However, due to the fact that the material introduced into each pocket during the early part of the blowing operation travels farther and at a higher velocity than the material later introduced into each pocket, the density of the material varies slightly between the top and the bottom of the package. While this is not objectionable with many kinds of prodnets and my earlier apparatus can fill the packages with very accurately controlled amounts of material by weight, nevertheless, it would be more economical to render the density of the material in the package completely uniform thereby to introduce somewhat more material into a package of given size, or to reduce the size of the package for a given weight of material.

The present invention has to do with methods and apparatus for packaging or introducing materials into wrappers or receptacles by means of a blowing apparatus and in which the material can be compacted after a definite and accurately measured quantity of material is blown into the package so that the material is rendered substantially uniform in density throughout the package thereby to enable an additional amount of the material 'to be introduced into a package of given size or to rebe overfilled and then compacted so as to bring the excess material within the confines of the package where it may be sealed by application of a cover sheet to the Reduction of package size or increases in the amount of fluent material in a package of as much as 8 to percent are obtained by compacting the materialafter its introduction into the package. The new method and apparatus also enables the use of lower blowing pressure, thereby preventing escape of material during filling of the packages. Nevertheless, the material can be packed in the packages more firmly and densely thereby imp-arting greater firmness to the contents and giving the packages enhanced resistance to deformation or damage by handling.

For a better understanding of the present invention, reference may be had to the accompanying drawings in which:

Figure 1 is a schematic view in side elevation of an apparatus shown of a type embodying the present invention;

Figure 2 is a view in side elevation of a portion of the apparatus illustrating details of the frame for clamp ing the packaging material to the molding apparatus;

Figure 3 is a view in section taken on line 33 of Figure 2, disclosing details of the mold and the blowing head, parts of the mold and blowing head being broken away; and

Figure 4 is a view in section taken on line 4'4-' of Figure 2, with a portion of the blowing head and clamping frame broken away.

The form of apparatus chosen for purposes of illustration is similar in a number of respects to the apparatus shown in my co-pending application Serial No. 585,- 775, filed May 18, 1956, and only those portions of the new apparatus which are new will be described and discussed in detail herein.

As shown in Figure 1, the apparatus includes a molding drum 10 of octagonal shape, although it may be of other polygonal shape or in the form of a chain mold, if desired. Each of the faces of the drum 10 carries a mold element 10A containing a series of molding cavities 11 and 12, each of which is illustrated as being generally V-shaped or triangular in cross section and having an open rectangular mouth. The apex portion of each mold cavity is formed of a V-shaped block 13 and 14 of porous metal by means of which suction can be exerted through suction lines or passages 15 and 16.

The molding drum 10 is mounted for intermittent rotation on a shaft 17 which is received rotatably in the bearings 19 of a pair of standards 20 on opposite sides of the drum. Each of the mold elements 10A is mounted for movement radially of the drum. Such radial movement is obtained by means of a pneumatic or hydraulic cylinder 21 for each mold element 19A having its piston 22 pivotably connected to and supporting a mold element 10A. Actuation of the pistons is produced by means of an air valve 23 under the control of a cam 24 driven by means of a motor 25 through suitable reduction gearing (not shown), the cam being mounted on a shaft 26 extending between the side plates 27 of the frame. A

cam. follower including a roller 28 and an arm or lever 29 pivotally supported on the side plate 27 engages the cam 24, and carries a plunger 30 for actuating the air valve. A coil spring 31 is interposed between lever 29 and the valve 23 normally biasing them apart. Air from the air valve is supplied to a fixed manifold 32 which has a port for supplying air to the uppermost cylinder.

Inasmuch as the cam 24 is provided with a low sec tion 33 and a longer high section 34, it will be apparent that rotation of the cam will close valve 23 when the roller 28 engages the low portion 33 of the cam and open the valve while the roller 28 is in contact with the raised portion 34 of the cam. Up and down movement of the mold element 10A at the top of the mold drum 10 is required in order to bring it into proper cooperating relation with the blowing head 35 which is supported in fixed position by means of arms 36 extending from the upper ends of the side plates 27 of the frame.

The blowing head 35 is similar to the blowing head shown in my application Serial No. 585,775 in that it includes a feed hopper 37 into which the fluent or finely divided material can be introduced. Directly below the hopper 37 is a control valve chamber or housing 38 which contains a pair of spherical or ball valves 39 and 40 each of which is provided with a .diarnetncal passage 41 and a radial passage 42. Valve seats 43 for each of the ball valves are mounted within the casing 38 and are supported by means of a detachable flange member 44 and an interposed wavy spring 45 so as to urge the seat against the lower portion of each ball valve. Each seat has complemental semi-spherically curved seating portions 47 and 48 and a relief area 49 above the seats.

Carried at the upper edge of each seat member 43 isa ring of porous sintered metal 50 by means of which air under pressure can be introduced into the space 51 surrounding the upper portion of the ball through an inlet and exhaust port 52.

A seal around the upper portion of each ball valve to prevent air from being blown upwardly into the hopper is afforded by means of the rubber sealing ring 53 which engages the upper portion of the ball 39 above the passage 41 when it is disposed horizontally. The ball valves 39 and 48 can be rotated so that the diametn'cal passage is disposed vertically to receive charges of fluent material delivered from the hopper 37 by means of a screw conveyor or in any other way.

The material in the valve chamber is discharged down into the hopper portion 55 of the blowing head disposed below the valves 39 and 40.

As shown, the hopper portion 55 has a pair of gen erally V-shaped cavities 56 and 57 therein each corresponding to one of the mold cavities 11 and 12 and to one of the valves. The valves are so related to the hopper portion 55 that the rate of feed of material from the hopper into the hopper portion is sufficient to keep the hopper portion 55 substantially full.

The operation of the blowing head is as follows. With the valves as shown in Figure 3, air pressure supplied through the port 52 will flow through the porous rings 50 in diffused form and into the opposite ends of the diametrical passage 41 where it exerts a pressure on the material therein to force it through the radial passages 42 and out of the hopper portion 55 and the chambers Y56 and 57 therein through the filling slots 59 and 60 into receptacles 11 and 12. Air displaced by the entry of the fluent material into the receptacles escapes through the porous metal bottom plate 61 of the hopper portion around the passages 59 and 6t and through the ports 62 and 63 on opposite sides of each of the passages 59 and 60. Fluent material cannot escape from the mold cavity through the porous metal plate 61 due to its fine porosity.

As illustrated best in Figures 3 and 4, the fluent material is not introduced directly into the mold cavities 1-1 and 12, although in some instances this may be done. The mold cavities 1'1 and 12 are lined with an enwrapment material M which may either be preformed or may be formed by heating and applying vacuum thereto as disclosed in my application Serial No. 585,775, to form a series of pockets 65 and 66 connected by thin web portions around their edges and between them. The pocket elements 65 and 66 are held in position by 'means of suction applied through the passages 15 and 16 and the porous filler blocks 13 and 14 in the bottoms of the molds 11 and 12. These passages 15 and 16 may be connected to a manifold centrally located with respect to the mold wheel 18 as disclosed in application Serial No. 585,775 to hold the enwrapment material in place. The enwrapment material M is further positioned by means of a gripping frame 68 of generally rectangular shape made of metal or the like and having a centrally located cross bar 69. The bottom edges 78 of the frame '68 and the bottom edge of the cross bar 69 are adapted to engage the web portions of the sheet around and between the pockets 65 and 66 and force them against the corresponding portions of the mold to hold them against distortion and to affect a seal around the edges of the pockets so that material cannot escape from the pockets during the blowing operation.

As shown in Figure 3, the side rails of the frame 68 have inturned flanges 72 around their inner edges which are disposed above the shoulders 73 extending around the hopper portion 55. A clearance space 74 is provided enabling the frame 68 and the cross bar 69 to move up and down between the position shown in Figure 3 and a retracted position substantially in the plane of the lower surface of the plate 61 as shown in Figure 4. The frame 68 is in substantially fluid-tight relation to the outside of the hopper portion 55. Movement of the frame 68 between the positions indicated is affected by means of a pair of cam rails 75 and 76 on opposite sides of the frame 68, the outer ends of the cam rails having inclined portions 77 and 78 engagea-ble with the follower rollers 79 and 80 mounted between the lugs 81 and 82 and the outer sides of frame 68. The upper edges of the cam bars 75 and 76 are straight and bear against rollers 83 and 84 rotatably mounted on the casing 38 of the blower head. The cam bars are guided for endwise movement by means of guide-ways 85 and 86 secured to the opposite sides of the casing '38.

Movement of the cam bars is produced by means of a slide member 89 which includes an inner cam element 98 having a pointed lower end or wedge-shaped lower end 901: engaging the rollers 91 and 92 on the inner ends of the cam rails 75 and 76. A guide member 93 fixed to the side of the casing 38 receives the cam element for vertical sliding movement. A bar member 95 of generally inverted T-shaped section is secured to the outer face of the cam element 90 and carries a pair of upwardly extending cam plates 96, 97 having outwardly diverging edges 98 and 99 which also cooperate with the rollers 91 and 92 when the cam member 89 is lifted to move the cam rails 76 and 77 toward each other. As shown in Figure 2, downward movement of the actuating element 89 causes the pointed or V-shaped cam element 90 to force the cam bars or rails 75 and 76 apart and the wedging or camming surfaces 78 and 77 thereon will force the frame 68 downwardly. Upward movement of the member 89 causes the cam elements 96 and 97 to engage the rollers 91 and 92 and move the cam bars '75 and 76 inwardly so that the frame 68 is free to move upwardly. It is not lifted upwardly by the action of the camming member.

Downward movement of the frame 68 is limited by means of the adjustable bolts 188, 181 arranged around the lower edge of the casing 38 and passing through openings in the flanges 102 and 103 extending outwardly from the frame 68. Upward movement is limited by the metal bushings 1184 so that uniform movement of the clamping frame 68 and uniform compacting are obtained.

Relative movement between the clamping frame 68 and the blowing head 35 is provided to allow compression of the material blown into the pockets 65 and 66. Referring to Figures 3 and 4, it will be apparent that during the blowing operation, as described above, the edges of the frame 68 and the cross bar 69 are disposed below the level of the porous plate 61. Accordingly, when the fluent material is introduced into the pockets, it can fill them to the level of the porous plate 61. When the camrning member 89 is lifted and the frame 68 is released thereby for upward movement, air under pressure in the cylinder 21 lifts the mold upwardly to the position shown in Figure 4 in which the porous plate 61 is in the plane of the webs between the pockets. This action causes compaction of the material in the pockets by squeezing out the air in the material through the plate 61. Upward movement of the clamping frame 68 and the cooperating mold element 10A is aided by the spring 109 on the push rod 110 which is connected at its upper end to a lever 111 mounted on pivot 11-2 on the casing of the blowing head 35 and by means of a link 113 connected to the cam member 89. It will be apparent that with the push rod 110 disposed in advance of the cam roller 28, the frame 68 will be moved downwardly before the uppermost mold element A is moved upwardly and that the clamping frame 68 will be permitted to move upwardly before the mold element is released for inward movement.

Rotation of the drum 1t] can be produced by means of any suitable intermittent drive such as the Geneva movement 115 disclosed in Fig. 1 which is designed to rotate the mold intermittently .and only when all of the mold elements 10A in their under positions. This can be accomplished by driving the Geneva gear 116 by means of the chain and sprocket drive 117 which connects it to the main drive shaft 26.

Proper timing of the blowing and filling of the blowing head can also be accomplished by a microswitch 120 actuated by a cam 121 mounted on the shaft 26. Blowing takes place only when the uppermost mold element 10A is in sealing engagement with the clamping frame 68. Relief of pressure in the blowing head by means of the solenoid valve 124 which is controlled by the microswitch also takes place before the clamping frame 68 is raised. Blowing (filling) and exhaust will occur while the web or sheet material is .tightly clamped between the mold and the clamping frame so that escape of the fluent material is reduced to a minimum.

-A typical operation of the apparatus is .as follows. Assuming that a web of thermoplastic material has been introduced into the mold cavities 11 and 12 underlying the molding head and shaped into conformity with the cavities, the rotation of the shaft 26 by the motor will first cause the cam 24 to lower the clamping frame 68 to clamp the sheet material around the edges of the mold cavity. Next, the cam 24 actuates the air valve 23 to raise the uppermost mold element 10A to engage it with the clamping frame 68 and grip the sheet maten'al therebetween.

Cam 121 then closes the microswitch 120- energizing the solenoid valve to supply air under pressure to the blowing head which is in the condition shown in Figure 3. Air flowing through the porous metal rings forces the fluent material out of the valves and discharges the material through the passages 59 and 60, thereby filling the pockets 65 and 66 in the web and displacing the air in the pockets outwardly through the porous plate 61 and the passages 62 and 63, to atmosphere. The blowing operation is then discontinued by opening of the microswitch 120 so that the solenoid valve then connects the blowing head to atmosphere. The air under pressure in the blowing head escapes outwardly through the porous metal rings 50 to the port 52 and through the solenoid valve so that the pressure in the blowing head and in the pockets 65 and 66 approximates atmospheric pressure. At about this time, the cam roller 113 rides off of the crest of the cam 24 allowing the clamping frame 63 to be moved upwardly. Upward movement of the clamping frame is caused by the expansion of the spring 109 and lifting of the mold element 10A 21 short distance by the air pressure in its corresponding cylinder 21. Upward movement of the mold element causes compaction of the fluent material by relative movement of the mold drum with respect to the porous plate 61 thereby and rendering the density of the material substantially uniform throughout. At the end of the compacting operation which is of short duration, the cam follower roller 28 runs off of the high portion of the cam onto the low portion, thereby closing the valve 23 and allowing the raised mold element 10A to move downwardly. At this time, the Geneva movement 115 operates to rotate the mold drum one-eighth of a turn. Also, substantially simultaneously therewith the valves spawn 69 and 40 are rotated in a clockwise or counter-clockwise direction to dispose the passage 41 therein vertically so that an additional charge of fluent material can be delivered into it and into the hopper portion 55 from the hopper 37. The valves 39 and 40 are then rotated to the position shown in Figure 3 preparatory to another filling operation and the sequence described above is repeated.

It will be understood that a crank mechanism driven from the shaft 26 and with an interposed intermittent drive cam 126 may be used for rotating the valves 39 and 40 between the positions mentioned.

The above-described mechanism permits packages to be formedand filled quickly and uniformly with materials which have been difiicult to handle before with the desired degree ofaccuracy. Actually, the variation in the amounts introduced into the packages by weight are so small as to be negligible even with high speed operation of the machine. The reason that the applicants machine is capable of producing a denser packing of the material is that the air is not trapped within the wrapper and the air in the packages is reduced to a minimum.

It will be understood that while reference is made to the use of air as a compressing medium, inert gases also may be used with materials that are subject to spoiling by oxidation. Moreover, it will be understood that the package will be completed by the application of a cover sheet to the open ends or sides of the packages as described in my application Serial No. 585,775.

Other variations such as change in the shape of the molding cavity from V-shaped to substantially square or rectangular are possible inasmuch as the material introduced into the pockets is deformable and fluent and thus does not introduce difiiculties in removing the packages from the mold cavities.

In view of the variations possible in the machine as indicated above, it will be understood that the abovedescribed form of the invention is illustrative.

I claim:

l. A method of filling receptacles comprising covering a receptacle having an opening therein with a member spaced from said'receptacle and opposing said opening, blowing a finely divided material into said receptacle to fill it and introduce additional material between said member and said receptacle, venting the gas from the receptacle while said member retains the material therein, and compacting the material-in the receptacle by moving said member and receptacle relatively toward each other while the gas is vented to enable the gas to be dissipated at least in part from the material.

2. A method of filling receptacles comprising forming flexible sheet material into a receptacle having an open side, covering the open side of the receptacle with a porous member having an inlet therethrough, blowing a finely divided material through said inlet into said receptacle with a gaseous medium under pressure to fill said receptacle, said gaseous medium escaping from said receptacle through said porous member, compressing said material in said receptacle by moving said porous member and said receptacle relatively to reduce the volume of the material in said receptacle and render the density of the material in said receptacle substantially uniform, and thereafter covering and closing the open side of said receptacle.

3. A method of filling receptacles comprising forming flexible sheet material into a receptacle having an open side, covering the open side of the receptacle with a porous member having an inlet therethrough, blowing a finely divided material through said inlet into said re ceptacle with a gaseous medium under pressure to fill said receptacle, said gaseous medium escaping from said receptacle through said porous member, moving said porous member and said receptacle relatively to compress the material in said receptacle to render the density of the material in said receptacle substantially uniform, and

, 7 thereafter covering and closing the open side of said receptacle.

4. A method of filling receptacles comprising blowing with a gas under pressure a finely divided material into a receptacle having an opening therein to admit the material and vent the gas therefrom, covering said opening with a member having a porous portion to restrain the material against escape and permit the gas in said receptacle and material to escape, and compressing the material in the receptacle by reducing the size of the space between said covering member and said receptacle to reduce the volume of the material in said receptacle while the opening is covered by said member to vent gas from said receptacle and the material therein during compression of said material.

5. The method set forth in claim 4 in which said receptacle is formed of flexible sheet material and comprising closing the opening in said receptacle after compress ing the material in the receptacle.

6. A method of filling containers having a predetermined capacity comprising introducing a container having an opening therein into a supporting member having a cover spaced from the container and opposing the opening therein to provide a space outside said container adjacent the opening therein, blowing a fluent material with a gas under pressure into said space and through said opening to fill the container and said space, and thereafter moving the cover and the container relatively to force the material in said space into said container to compact the material in said container and render it substantially uniform in density.

7. A method of filling receptacles comprising blowing a finely-divided material into a receptacle having a cover provided with an opening and having a porous portion therein through which gas is vented from the receptacle while retaining the material therein, and thereafter reducing the size of the space enclosed by the receptacle and cover to compact the material therein While gas is vented through the porous portion to enable the gas to be dissipated at least in part from the material.

8. An apparatus for filling receptacles comprising a member having a cavity therein to receive a finely divided material, a filling device for blowing said finely divided material suspended in a gaseous medium into said cavity, a plate element overlying said cavity and having a porous portion enabling venting of said gaseous medium from said cavity while retaining the finely divided material therein, and means for moving said member and said plate element relatively to compress the material in said cavity to substantially uniform density.

9. An apparatus for filling receptacles comprising means for supporting a receptacle having an opening therein, a filling device overlying said supporting means and having a filling opening for introducing fluent material therethrough into said receptacle, means for applying gas pressure to said fluent material to force it through said filling opening into said receptacle, a plate member on said filling device having a porous portion overlying the opening in said receptacle and movable relative to said supporting means, said porous portion enabling escape of gas from said receptacle while retaining the fluent material therein, and means for moving said plate member and said supporting means relatively to compress the fluent material in said receptacle to substantially uniform density.

10. An apparatus for filling receptacles with fluent materials comprising a mold member having at least one cavity therein for receiving a sheet of material having a receptacle therein substantially fitting said cavity, a filling device adjacent to said mold member including a hopper portion to receive fluent material, a bottom plate for said hopper portion having a porous portion and a filling opening therein, means for moving said mold member and said filling device relatively to position said recep- ;tacle adjacent to said bottom plate, clamping means movable relative to said filling device and said mold member for clamping said sheet against said mold member and forming -a substantially gas-tight connection between said filling device and said receptacle, means for directing gas under pressure into said hopper portion to blow fluent material therefrom into said receptacle through said filling opening, said porous portion enabling gas to escape from the receptacle thereby to fill said receptacle with said fluent material, and means for moving said mold member and clamping means and said bottom plate relatively to compress the material in said receptacle.

11. The apparatus set forth in claim 10 in which said clamping means comprises a frame-like member mounted on said filling device for movement toward and away from said mold member, and the means for moving the mold member includes means for moving said mold member and the clamping member simultaneously in the same direction bringing said mold member closer to said bottom plate after the receptacle is filled.

12. The apparatus set forth in claim 10 in which said clamping means is a frame-like member mounted on said filling device for movement toward and away from said mold member, said apparatus comprising mechanism for alternately retaining said frame-like member in engagement with said sheet and releasing said frame-like member for movement with said mold member relatively to said bottom plate to compress said material.

13. An apparatus for filling receptacles comprising a blowing head having a hopper portion, means for supplying fluent material to said hopper portion, a bottom plate on said hopper portion having a filling opening and a porous portion adjacent thereto and means for directing gas under pressure into said hopper portion to blow said fluent material out of said filling opening, a member adjacent to said blowing head having means thereon to receive a receptacle having an open side, means for moving said blowing head and said member relatively to position said open side adjacent to said bottom plate and encompassing said filling opening and said porous portion, means for substantially sealing said blowing head to said receptacle to enable the fluent material to be blown into said receptacle while the gas escapes through said porous portion, and means for moving said receptacle relative to said bottom plate after said receptacle is filled to compress the material in said receptacle.

14. The apparatus as set forth in claim 13 in which the means for sealing the blowing head to the receptacle comprises a frame member mounted on said blowing head for movement toward and away from said receptacle-receiving member, said member surrounding said bottom plate, said apparatus comprising an intermittentlyactuated mechanism for retaining said frame member in a first position projecting beyond the bottom plate and releasing it for movement with said receptacle into a position substantially flush with said bottom plate.

15. The apparatus set forth in claim 14 in which said intermittently-actuated mechanism comprises at least one wedge-like cam member mounted for reciprocation transversely of said blowing head, surfaces on said frame-like member and said blowing head engaging said cam member and additional camming members mounted on said blowing head for moving said wedge-like cam member relative to said surfaces.

16. An apparatus for filling receptacles comprising a frame, a filling head fixed to said frame, a member having a plurality of cavities in its periphery for receiving receptacles connected together by and formed in a sheet of flexible deformable material, means supporting said member in said frame for rotation relative to said filling head and for movement to'ward and away from said filling head, means for alternately rotating said member a fraction of a revolution and moving it toward and away from said filling head, a sealing frame mounted on said filling head for engagement with the periphery of said member to seal the filling head to the sheet when the member is moved toward said filling head, mechanism for alternately restraining movement of said frame relative to said filling head to limit the movement of said receptacles toward said filling head and releasing the frame to enable the receptacles to move closer to the filling head, said filling head having a bottom plate overlying said receptacles in said member and containing an opening through which material is introduced from said filling head into said receptacles, said bottom plate acting to compress the material during movement of said receptacles closer to said filling head.

17. The apparatus set forth in claim 16 in which said filling head comprises a hopper portion above said bottom plate to receive a fluent material, valve means above said hopper portion alternately operative to admit fluent material into said hopper portion and to prevent back flow from said hopper portion, means for alternately directing gas under pressure into said hopper portion and for venting the gas from said hopper portion, said bottom 20 plate having at least one filling opening therein for introducing the material by said gas pressure into a corresponding receptacle and a porous portio'n for venting gas from said receptacle while the material is being intro- 25 duced into it.

18. Filling apparatus comprising a receptacle having a portion defining a cavity and a portion forming a cover for the cavity and having an opening therein, at least a part of one of said portions being formed of porous material, a filling device for blowing finely-divided material through said opening into said receptacle, said porous part retaining said material in said receptacle and venting gas therefrom during filling of the receptacle, one of said portions of said receptacle being movable toward the other one of said portions to reduce the volume of said receptacle to compact the material therein while gas is vented through the porous part of one of said portions, and means for moving said movable portion toward and away from said other one of said portions.

References Cited in the file of this patent UNITED STATES PATENTS 2,365,920 Vaughn Dec. 26, 1944 2,423,358 Wheaton et a1 July 1, 1947 2,493,652 Bowersox Jan. 3, 1950 2,540,059 Stirn et a1. Jan. 30, 1951 2,611,938 Hansberg Sept. 30, 1952 2,663,128 Stirn et a1. Dec. 22, 1953 2,780,247 Claassen Feb. 5, 1957 2,815,621 Carter Dec. 10, 1957 

